The objective of the SCOR program is to evaluate the role of environmental and immunologic factors on the genesis of hypersensitivity pneumonitis. The aims of the investigations are to develop means of early diagnosis, characterize the various forms and etiologic agents involved in the disease, define the immunologic mechanism(s) involved in its pathogenesis by means of animal models. The program is a consortium of investigators from the Medical College of Wisconsin, Milwaukee, the Marshfield Medical Foundation in Marshfield, WI and Northwestern University Medical School, Chicago, IL.